The present invention relates to a device for foaming a liquid, in particular milk, the device comprising a steam supply unit for operating a turbine positioned inside a casing, as well as a device for supplying air, wherein the turbine is connected by a shaft to an agitator for whirling the liquid.
International Patent Application Publication No. WO 90/10411 discloses a device for foaming and simultaneously heating a liquid such as milk, wherein a turbine wheel driven by hot steam functions to suction the liquid to be foamed into an emulsifying cage where the liquid is whirled. The disadvantage of this device is that the liquid to be foamed is in direct contact with the turbine wheel, thus making it possible for contaminants to be deposited which are the difficult to remove. In addition, the turbine wheel is designed to simultaneously function as an agitator, which is a disadvantage since the turbine rotation is not optimally directed toward the generating of foam.
A device for generating milk foam is disclosed in German Patent document DE 100 50 719, wherein a turbine wheel attached to a pipe operates an agitator arranged at the end of the pipe. The pipe is furthermore provided with air-intake openings and slots for suctioning in the milk. The milk thus enters a region on the inside of the pipe and is then transported to the agitator where it is foamed. As a result, contaminants that are hard to remove can be deposited on the inside of the pipe.